Single‐atom catalysts have become a popular choice in various catalysis applications, as they take advantages of both homogeneous catalysis (e.g., high efficiency) and heterogeneous catalysis (e.g., easy catalyst recovery). The atom support plays an indispensable role in anchoring atomic species and interplaying with them for ultimate catalytic performance. Therefore, development of new support materials for superior catalysis is of great importance. Here the synthesis of carbon nanofibers based on the reaction between phosphorus pentoxide (P2O5) and N‐methyl‐2‐pyrrolidone (NMP) is reported. The underlying reaction process is systematically investigated by Fourier‐transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The carbon nanofibers have interesting PN units in their chemical structure, which act as anchoring sites for the single‐atom catalyst. The Pt atoms anchoring carbon nanofibers exhibit high activity for hydrosilylation with a turnover frequency (TOF) of 9.2 × 106 h−1 and a selectivity of >99%. This research affords not only a new in situ chemical strategy to synthesize multiatom doped carbon nanofibers but also presents a potential superior support in catalysis, which opens a hopeful window in materials chemistry and catalysis applications.